With musical biopics, so often the most crucial element — the music — becomes a solo act, accompanied by little-to-nothing in the way of strong visual corollaries to that music. You get the outline of a tormented genius’ life, and a misguided, reverential sense of respect, but no cinema; no life in that life.

Don Cheadle’s “Miles Ahead” is a disarming exception to the usual. It’s squirrelly and exuberant. Even with what you might call a necessary evil at its center (more on that later), the film responds in storytelling terms to its subject’s jagged edges and dislocated state of mind. Cheadle, who stars in a role he w